Study on optical, electrochemical and thermal properties of the Meldrum
acid 5-aminomethylene derivative
VIBRATIONAL SPECTROSCOPY, (2021)DOI: 10.1016/j.vibspec.2020.103188
Abstract
The vibrational, optical, electrochemical and thermal properties of
Meldrum acid derivative 5-aminomethylene 5 - (2-hydroxyanilino)
methylidene -2,2-dimethyl-1,3-dioxane-4,6-dione (HYM) were investigated
combining Infrared and Raman spectroscopy at room temperature assisted
by DFT calculations, UV-vis spectroscopy assisted by TD-DFT
calculations, cyclic voltammetry and thermal analysis. The B3LYP / 6
311++G(d, p) calculations led to the identification of the minimums on
the potential energy surfaces of the molecule, from these calculations
the most stable conformer in relation to the dihedral angle C8-N1-C7-C4
was predicted at 360.. Comparison between experimental and theoretical
vibrational spectra provides an accurate understanding of the
fundamental vibrational modes and leads to a better interpretation of
experimental Raman and infrared spectra. The vibrational mode assignment
given in terms of potential energy distribution analysis (PED) leads us
to a broader interpretation of the vibrational spectra of the
investigated material. The UV-vis spectrum of the compound was recorded
in the region between 200 and 450 nm and the HOMO and LUMO electronic
properties were calculated by TD- DFT. The gap energy calculated from
the difference between the HOMO and LUMO orbitals was obtained with a
value of 4.52 eV. The HYM is thermally stable up to 142 degrees C based
on data obtained from TG-DTA analysis.